DEALING WITH RHINOCEROS BEETLE INFESTATION THROUGH BIOLOGICAL AND NATURAL APPLICATIONS AND METHODS Using the fungus Metarrhizium anisopliae as part of an integrated pest management system By Catherine Dallaire and Dr. Margret Rueffler Oryctes Rhinoceros L. is an endemic pest of Asia that causes devastating damages to coconut palm tree plantations. What is an effective method to organically and naturally modify the number of the coconut beetles? Jiwa Damai, a permaculture garden located in Bali, Indonesia, has been under the attack of the Rhinoceros beetle (Oryctes Rhinoceros L.) for a period of two years. This pest infestation has highly endangered the coconut palm tree population and reduced the coconut oil production. This paper presents the integrated pest management system, composed of several layers of actions, that has been applied by this farm in order to face this issue. This control method is based on ecological principles that aim to strengthen the coconut palm trees and reduce the beetle population to a level that no longer treathens the tree’s survival. This method relies heavily on the utilization of the fungus Metarrhizium anisoplia as a biocontrol agent for Oryctes Rhinoceros L. One month after the application of the fungus, the number of insects has reduced by 50% in the upper part of the trees and the number of larvae, pupae and insects has reduced by 90% in the compost piles. However, monitoring the effects of this control method on a long term basis is essential to pursue a good assessment of its effectiveness. 1. Introduction: our local situation Jiwa Damai, permaculture garden and retreat center is located in the center of the island of Bali, Indonesia (www.jiwadamai.net). The garden is based on permaculture principles; therefore, only fully organic methods are used. Any chemical products - pesticides, insecticides, conventional fertilizers - are not applicable. The garden is surrounded by a vast natural forest containing 180 coconut palm trees scattered throughout the area. Signs of damages on coconut palm trees appeared 2 years ago, with leaves turning brown, falling down and dying, as well as fronds appearing on coconut tree branches. These symptoms allowed us to identify the presence of a possible pest infestation. Discussion with other local farms informed us about the appearance of Rhinoceros beetles in our region. Inspecting the coconut palm trees afterwards revealed the presence of numerous adult insects located in the tree crowns. About 80% of all our coconut palm trees exhibited insects in their upper part. The number of visible beetle holes on branches (see annex 1), varied from 1 to 8 per tree. However, trees with only 1 visible hole in a branch still showed a high number of damaged leaves. No physical damages appeared on tree trunks. Six months later, some larvae were also discovered in our compost piles. Since that time, four coconut palm trees were already dead and had to be cut down, the trunk heavily infested, due to beetle attacks. From then on damages appeared on almost all of our trees. Moreover, large numbers of Rhinoceros beetle larvae, pupae and adults have now been discovered in our compost piles in the past few months. Up to hundreds of larvae and adults were discovered in the biggest compost pile (2 x 4 x 1 cubic meters) (see annex 2). This pile was composed of sugar palm trunks and it seems to be a favorite place for the beetle to place the larvae. Digging the soil around the coconut palm trees also revealed some larvae in the earth scattered close to the tree roots. From 1 to 5 larvae could be found around the roots in average. We discovered that dead sugar palm trees and our organic compost were major breeding sites for the larvae. The common knowledge presumes that the beetle breeding in the sugar palm trunks was a different kind of beetle. However, our own experience indicates that coconut palm Rhinoceros beetles will use dead, decaying or damaged sugar palm trees as breeding sites. These signs of damages lead us to the conclusion that the beetle population was excessive and was a real threat to the coconut palm trees and our coconut oil production was reduced due to a lesser coconut harvesting. 2. History of Rhinoceros beetle Oryctes Rhinoceros (L.) (commonly called Rhinoceros beetle) is now endemic to Asia; India, Maldive Islands, Taiwan, Thailand, Vietnam, Malayan Peninsula, the islands of Java, west Pakistan, Sumatra, Bali, Lombok and the Philippine Islands (Bedford 1980). The beetle is autochthonous from South-east Asia and was introduced in the South Pacific in the 50s, causing devastating damages to coconut palm tree plantations (Huger 2005). Chemical products were used as a first resort solution at that time, leading to massive utilization of pesticides in an attempt to eliminate the beetle (Huger 2005). Due to the physiological characteristics and the living habits of the adult beetle and the larvae, insecticides showed no conclusive effectiveness in reducing the beetle populations (Huger 2005). For this reason, a new interest was developed for using biological control methods. Some research programs attempted to apply biocontrol methods worldwide, including the Oryctes virus that was distributed in several countries in order to reduce the population in the 70s and 80s (Jackson 2005). This baculovirus showed impressive success in reducing the number of beetles at that time. However, recent devastating outbreaks of the beetle show that this control method is no longer as effective as before. Furthermore, the virus has demonstrated genetic variation, which leads to doubts about its characteristics and effects in the long term (Jackson 2005). As declared by the FAO, strategies based on the use of chemical products are unsustainable and inefficient (FAO 2004). These factors contribute to the need for exploring new techniques for controlling pest outbreaks in the coconut growing regions of Asia. As these insects attack not only the adult trees, but also young trees and seedlings, their impact can be very damaging to a plantation. When invading a site, their widespread and multiple breeding sites are difficult to destroy or remove completely. Dead trees, killed by adult insects or other sources (disease, physical damage, lightning strikes, …) serve as breeding sites for the larvae (Bedford). Other locations for Rhinoceros beetle larvae may be compost, decaying wood, heaps of sawdust, animal manure or any decaying material (Bedford 1980). Larvae show strong negative phototaxis behaviors, select high humidity (85-95%) areas and prefer temperatures between 27-29 celsius degres (Bedford 1980). The main factors affecting the density of a beetle population on a site is the availability of breeding sites in the area and the density of accessible food supplies. Adult beetles are usually located in the crown of palm trees for feeding and larvae are found at the ground level in the breeding sites (Hallet et al 1995). The adult beetle attacks the trees on multiple areas, which makes it hard to evaluate the scope of an infestation. Feeding on unopened leaves and tissue juices, the adult beetles get inside the tree by the growing points of the tree (Bedford 1980). This causes damages to inflorescences which reduces the general photosynthetic activity of the tree and diminishes or completely stops fruit production. As said by Bedford (1980), a tree with 50% of its fronds damaged is likely to produce only one fifth of its normal fruit production, as coconut palm trees react with a drop-off of immature button nuts when loosing inflorescences. Damages to opened leaves and defoliation can lead to death of young and mature trees. Moreover, opened fronds and damaged growing points enhance the risks of pathogen attacks and the wounds provide entry points for other insect pests (Hallet et al 1995). Asian palm weevil infestations, which is another important pest for coconut palm trees, can then become a major risk to the trees (Hallet et al 1999). Moreover, as the damages of a Rhinoceros beetle infestation are irregular and located on various tree parts, different control methods need to be implemented in order to be effective on each area. This complexity reinforces the need for a multi- approach control method, with effective techniques that focus on reducing the number of beetles without injuring the tree and the surrounding environment. As total eradication of the beetle in Asia was shown to be impossible for the last decades (Bedford 1980), implementing efficient population control methods is imperative to stop the decline in coconut palm tree number. Knowing that females can lay from 49 to 60 eggs on average (Bedford 1980), we can expect this already excessive population to grow even bigger in the next few months if nothing is done in our garden. 3. Our action plan Working in cooperation with local specialists and reading other case studies allowed us to develop a plan of action based on the utilization of multiple control methods simultaneously. This integrated pest management system focuses on using ecologically based methods that reduce the number of beetles and larvae on our site without damaging the surrounding environment and creating any negative feedback effects. Our approach does not aim to completely eradicate the beetle from our environment, but only to control the population in order to achieve a state of balance that no longer threatens coconut palm tree survival. 3.1 Monitoring Monitoring tree damages and symptoms is an important part of this system. In order to assess the efficiency of our control method, we numbered each coconut palm tree from 1 to 160 and separated the land in three distinct areas. This was done with the aim of keeping track of the beetle population evolution and change. Sketching a map of the area is our next goal in order to precisely locate the beetle’s hotspots and movements through time.